Print refs for k (visualization tool)

how_to/Change_26.md

@@ -0,0 +1,14 @@
+- k: Print refs
+
+Now that we have refs and a potentially branching commit history, it's a good
+idea to create a visualization tool to see all the mess that we've created.
+
+The visualization tool will draw all refs and all the commits pointed by the refs.
+
+Our command to run the tool will be called `ugit k`, similar to `gitk` (which is
+a graphical visualization tool for Git).
+
+We'll create a new `k` command in *cli.py*. We'll create `iter_refs` which is a
+generator which will iterate on all available refs (it will return HEAD from the
+ugit root directory and everything under *.ugit/refs*). As a first step, let's
+just print all refs when running `k`.

ugit/cli.py

@@ -56,6 +56,9 @@ def parse_args():
     tag_parser.add_argument("name")
     tag_parser.add_argument("oid", default="@", type=oid, nargs="?")
 
+    k_parser = commands.add_parser("k")
+    k_parser.set_defaults(func=k)
+
     return parser.parse_args()
 
 
@@ -104,3 +107,9 @@ def checkout(args):
 
 def tag(args):
     base.create_tag(args.name, args.oid)
+
+
+def k(args):
+    for refname, ref in data.iter_refs():
+        print(refname, ref)
+    # TODO visualize refs

ugit/data.py

@@ -1,6 +1,7 @@
-from pathlib import Path
+from pathlib import Path, PurePath
 
 import hashlib
+import os
 
 GIT_DIR = ".ugit"
 
@@ -24,6 +25,16 @@ def get_ref(ref):
             return f.read().strip()
 
 
+def iter_refs():
+    refs = ["HEAD"]
+    for root, _, filenames in Path.walk(f"{GIT_DIR}/refs"):
+        root = PurePath.relative_to(root, GIT_DIR)
+        refs.extend(f"{root}/{name}" for name in filenames)
+
+    for refname in refs:
+        yield refname, get_ref(refname)
+
+
 def hash_object(data, type_="blob"):
     obj = type_.encode() + b"\x00" + data
     oid = hashlib.sha1(obj).hexdigest()